In most rear wheel drive vehicles, a source of rotational energy, such as an internal combustion or diesel engine, is located near the front of the vehicle. The engine is connected by means of a drive line to rotate one or more driven wheels, which are located near the rear of the vehicle. The drive line typically extends between a transmission, which is connected to the engine, and a differential, which is connected to an axle assembly and the driven wheels. In some vehicles, the distance separating the transmission and the differential is relatively short. In these vehicles, the drive line is composed of a single piece, jointed assembly which is usually referred to as a driveshaft. In other vehicles, the distance separating the transmission and the differential is relatively long, making the use of a one-piece driveshaft impractical. In these vehicles, the drive line is composed of a driveshaft and one or more coupling shafts. The coupling shafts are connected to the driveshaft (and to each other) by couplings.
Driveshaft couplings require a certain degree of flexibility to handle the axial displacement that occurs between the coupling shafts during rotation, especially at higher speeds and under driving conditions. Universal joints are commonly used to accommodate for the angular misalignment that occurs between the axes of intersecting shafts. Many other types of couplings are also known in the art, such as link-type couplings, Oldham's couplings, and variations thereof. However, these couplings have rigid components and therefore provide limited dampening properties under high torsional loads. These couplings are therefore associated with a higher degree of torsional disturbances during driving such as undesirable vibration or noise.
More recently, elastomeric flexible couplings have been introduced to provide for improved dampening properties and absorption of torsional loads. Some elastomeric couplings have internal fibers to assist in absorbing the torsional load during rotative operation. These couplings are placed between metal disks affixed to the ends of the two adjoining coupling shafts, similar to placing a rubber gasket between two metal half-flanges. However, the gasket-like flanges offer limited flexibility for angular misalignment between the intersecting shafts. Furthermore, torsional loads are not well distributed within the couplings due to the bending of internal fibers that occurs during rotation.
It would be desirable to create an elastomeric coupling with internal tensile members, wherein the coupling provides high angular flexibility while maintaining the internal tensile members in tension during angular operation for optimized torsional dampening effects.